Biology subjects

Whitworth, C. P.

Publications and source records attributed to Whitworth, C. P..

3 recordsLinked to original sources

bioRxiv2024

Dysfunctional mechanotransduction regulates the progression of PIK3CA-driven vascular malformations

Somatic activating mutations in PIK3CA are common drivers of vascular and lymphatic malformations. Despite common biophysical signatures of tissues susceptible to lesion formation, including compliant extracellular matrix and low rates of perfusion, lesions vary in clinical presentation from localized cystic dilatation to diffuse and infiltrative vascular dysplasia. The mechanisms driving the differences in disease severity and variability in clinical presentation and the role of the biophysical microenvironment in potentiating progression are poorly understood. Here, we investigate the role of hemodynamic forces and the biophysical microenvironment in the pathophysiology of vascular malformations, and we identify hemodynamic shear stress and defective endothelial cell mechanotransduction as key regulators of lesion progression. We found that constitutive PI3K activation impaired flow-mediated endothelial cell alignment and barrier function. We show that defective shear stress sensing in PIK3CAE542Kendothelial cells is associated with reduced myosin light chain phosphorylation, junctional instability, and defective recruitment of vinculin to cell-cell junctions. Using 3D microfluidic models of the vasculature, we demonstrate that PIK3CAE542Kmicrovessels apply reduced traction forces and are unaffected by flow interruption. We further found that draining transmural flow resulted in increased sprouting and invasion responses in PIK3CAE542K microvessels. Mechanistically, constitutive PI3K activation decreased cellular and nuclear elasticity resulting in defective cellular tensional homeostasis in endothelial cells which may underlie vascular dilation, tissue hyperplasia, and hypersprouting in PIK3CA-driven venous and lymphatic malformations. Together, these results suggest that defective nuclear mechanics, impaired cellular mechanotransduction, and maladaptive hemodynamic responses contribute to the development and progression of PIK3CA-driven vascular malformations.

bioengineering↗

bioRxiv2023

Aminobisphosphonates reactivate the latent reservoir in people living with HIV-1

Antiretroviral therapy (ART) is not curative due to the existence of cellular reservoirs of latent HIV-1 that persist during therapy. Current research efforts to cure HIV-1 infection include "shock and kill" strategies to disrupt latency using small molecules or latency-reversing agents (LRAs) to induce expression of HIV-1 enabling cytotoxic immune cells to eliminate infected cells. The modest success of current LRAs urges the field to identify novel drugs with increased clinical efficacy. Aminobisphosphonates (N-BPs) that include pamidronate, zoledronate, or alendronate, are the first-line treatment of bone-related diseases including osteoporosis and bone malignancies. Here, we show the use of N-BPs as a novel class of LRA: we found in ex vivo assays using primary cells from ART-suppressed people living with HIV-1 that N-BPs induce HIV-1 from latency to levels that are comparable to the T cell activator phytohemagglutinin (PHA). RNA sequencing and mechanistic data suggested that reactivation may occur through activation of the activator protein 1 signaling pathway. Stored samples from a prior clinical trial aimed at analyzing the effect of alendronate on bone mineral density, provided further evidence of alendronate-mediated latency reversal and activation of immune effector cells. Decay of the reservoir measured by IPDA was however not detected. Our results demonstrate the novel use of N-BPs to reverse HIV-1 latency while inducing immune effector functions. This preliminary evidence merits further investigation in a controlled clinical setting possibly in combination with therapeutic vaccination.

microbiology↗

bioRxiv2022

Microphysiological vascular malformation model reveals a role of dysregulated Rac1 and mTORC1/2 in lesion formation.

Somatic activating mutations of PIK3CA are associated with the development of vascular malformations (VMs). Here, we describe a microfluidic model of PIK3CA-driven VMs consisting of human umbilical vein endothelial cells (HUVECs) expressing PIK3CA activating mutations embedded in 3D hydrogels. We observed enlarged and irregular vessel phenotypes, consistent with clinical signatures and concomitant with PI3K-driven upregulation of Rac1/PAK, MEK/ERK, and mTORC1/2 signaling. We observed differential effects between Alpelisib, a PIK3CA inhibitor, and Rapamycin, an mTORC1 inhibitor, in mitigating matrix degradation and vascular network topology. While both drugs are effective in preventing vessel enlargement, Alpelisib suppressed mTORC2-dependent AKT1 phosphorylation and MEK/ERK signaling. Rapamycin failed to reduce MEK/ERK and mTORC2 activity and resulted in vascular hyperbranching, while inhibiting PAK, MEK1/2, and mTORC1/2 signaling mitigates abnormal growth and vascular dilation. Collectively, these findings establish an in vitro platform for modeling VMs and confirm a role of dysregulated Rac1/PAK and mTORC1/2 signaling in PIK3CA-driven VMs.

bioengineering↗